og-127新问题～

127. In theory, international civil servants at the United Nations are prohibited from continuing to draw salaries from their own governments; in practice, however, some governments merely substitute living allowances for their employees' paychecks. assigned by them to the United Nations.

(A)  for their employees' paychecks, assigned by them

(B)  for the paychecks of their employees who have been assigned

(C)  for the paychecks of their employees, having been assigned

(D)  in place of their employees' paychecks, for those of them assigned

(E)   in place of the paychecks of their employees to have been assigned by them

答案是b没有错，但是有一点我还是不大明白，b中的the paychecks of their employees可以这么说么？难道不是the paychecks of their employees'么，就是像the desk of mine 的表达一样？

马上要考了，烦请大家看一下哈～感激不尽！